Faculty Bibliography

BACKGROUND: Schizophrenia patients have difficulty mastering even rote procedural tasks in rehabilitation settings. Although most studies demonstrate intact procedural learning in schizophrenia, recent findings demonstrate that a critical component of procedural learning is dependent on sleep. This study tested the hypothesis that patients with schizophrenia have a deficit in sleep-dependent procedural learning. METHODS: Using a simple, well-characterized test of motor skill learning, the finger tapping motor sequence task (MST), 26 patients with chronic, medicated schizophrenia and 14 demographically matched healthy control subjects were tested on two occasions, 24 hours apart. The main outcome measures were learning of the MST on day 1 (practice-dependent learning) and overnight, sleep-dependent improvement in performance. RESULTS: Although schizophrenia patients and control subjects did not differ in practice-dependent learning, patients failed to show overnight improvement (4% deterioration) and differed significantly from control subjects who showed a significant 11% improvement. CONCLUSIONS: We present here the first demonstration of a failure of sleep-dependent consolidation of procedural learning in chronic, medicated schizophrenia. This deficit occurred in the context of normal practice-dependent learning within a training session. This behavioral dissociation is consistent with evidence that practice- and sleep-dependent motor learning reflect independent processes and suggests that they are differentially affected in schizophrenia

Antisaccades have not only longer latencies but also lower peak velocities than prosaccades. It is not known whether these latency and velocity differences are related. Studies of non-human primates suggest that prosaccade peak velocity declines as latency from target appearance increases. We examined whether a similar relationship between peak velocity and latency existed in human saccades, whether it accounted for the difference in peak velocity between antisaccades and prosaccades, and whether it was affected by schizophrenia, a condition that affects antisaccade performance. Sixteen control and 21 schizophrenia subjects performed prosaccade and antisaccade trials in the same test session. In both groups antisaccades had lower peak velocities than prosaccades. Latency did not influence the peak velocities of antisaccades in either subject group. At short latencies, the peak velocities of prosaccades were also similar in the two groups. However, while prosaccade peak velocities declined minimally with increasing latency in control subjects, those in the schizophrenia group declined significantly until they reached a value similar to antisaccade peak velocities. We conclude that, in normal subjects, the effect of latency on prosaccade peak velocity is minimal and cannot account for the lower velocity of antisaccades. In schizophrenia, we hypothesize that the latency-related decline in prosaccade peak velocity may reflect either an increased rate of decay of the effect of the transient visual signal at the saccadic goal, or a failure of the continuing presence of the target to sustain neural activity in the saccadic system

BACKGROUND: Attitude toward medications is important for medication adherence. A patient's drug attitude probably reflects a weighing of benefits against experienced or anticipated side effects or risks associated with the medication. We predicted (1) that drug attitudes would be more positive among schizophrenia patients taking second-generation compared to first-generation antipsychotics because of their greater tolerability and efficacy; and (2) that greater insight into illness, fewer extrapyramidal symptoms, and better social functioning would be associated with better attitudes toward psychiatric medication. METHOD: In a cross-sectional study of 81 DSM-IV-diagnosed schizophrenia outpatients, we used multivariate analysis to determine clinical and demographic predictors of drug attitude. Drug attitude was assessed with the 10-item Drug Attitude Inventory (DAI). The relationship between the DAI and psychopathology, insight, extrapyramidal symptoms, level of functioning, and type of antipsychotic (first-generation versus second-generation versus clozapine) was examined. RESULTS: Less awareness of current symptoms, presence of deficit symptoms, and employment predicted a negative attitude toward psychiatric medications. Extrapyramidal symptoms did not predict drug attitude. Drug attitudes were no different between patients taking first- or second-generation antipsychotics or clozapine. CONCLUSION: Patients may not favor second-generation over first-generation antipsychotics, and extrapyramidal symptoms may not be a primary factor determining attitudes. While attitudes may be more positive in patients who recognize therapeutic drug effects, patients who work may view medications particularly negatively, possibly due to a sense of stigma. Because drug attitudes may reflect compliance and are difficult to predict, clinicians should inquire directly

OBJECTIVE: Because glutamate carboxypeptidase II (GCPII) regulates both folate absorption and activation of N-methyl-d-aspartic acid receptors, the authors examined relationships between serum folate concentrations and clinical symptoms in schizophrenia patients. METHOD: For 91 outpatients with schizophrenia, clinical assessments were performed and serum folate, homocysteine, B(12), glycine, and serine concentrations were measured. RESULTS: Serum folate concentrations were significantly lower than in a representative sample from the Framingham Offspring Study. Folate concentration correlated inversely with the Scale for Assessment of Negative Symptoms total score and was lower in patients with the deficit syndrome than in nondeficit patients. Homocysteine concentration correlated with the severity of extrapyramidal symptoms. CONCLUSIONS: These findings could reflect several possible mechanisms, including low dietary intake of folate, low GCPII activity, cigarette smoking, and the involvement of folate in the synthesis of neurotransmitters. Additional studies are needed to clarify these findings

OBJECTIVE: Examine whether frontal lobe dysfunction or affective experiences correlates with lack of symptom awareness in schizophrenia. METHOD: A total of 122 consecutive adult schizophrenia outpatients were assessed cross-sectionally with standard rating scales of psychopathology and of insight, and underwent neuropsychological assessment with a battery of tests sensitive to frontal lobe dysfunction. Correlational analyses were used to determine relationships between variables. RESULTS: About 62% of patients had at least partial awareness of symptoms. Anxiety correlated modestly with insight into the abnormal nature of positive and negative symptoms. No cognitive variable was significantly correlated with symptom awareness. CONCLUSION: The pathological nature of symptoms is better recognized by patients who experience dysphoric affect. Neither severity of psychotic symptoms nor frontal lobe cognitive deficits correlates to symptom awareness. Lack of insight, which can be partial for symptoms of the illness, might be a non-reducible symptom of schizophrenia.

BACKGROUND: Patients with schizophrenia have smaller hippocampal volumes and perform abnormally on most declarative memory tasks. Although these findings are likely related, the impact of hippocampal pathology on cognitive performance in schizophrenia remains unclear. This study examined this relationship by measuring the volume of the hippocampus and its activation during memory task performance. METHODS: Participants included 15 patients with schizophrenia and 16 age-matched control subjects. Hippocampal volume was determined via three-dimensional volumetric analysis of high-resolution magnetic resonance images. Hippocampal activity was assessed by measuring changes in blood oxygen level-dependent signal during a recognition memory task. RESULTS: Patients with schizophrenia had smaller hippocampal volumes bilaterally and demonstrated poorer performance on the recognition memory task, largely because of a heightened rate of false alarms to novel stimuli. Both groups showed robust hippocampal activity to old and new items when compared with a low-level baseline task; however, direct comparison of hippocampal activity during recognition task performance revealed that healthy control, but not the schizophrenia, subjects showed significant right anterior hippocampal activation during the evaluation of novel items. CONCLUSIONS: The impaired ability to classify new items as previously not experienced is associated with decreased recruitment and smaller volume of the hippocampus in schizophrenia.